Solar UV radiation and temperature effects on fatty acids of Microcystis aeruginosa

Abstract

One of the most common regulatory strategies to adapt to stress is by adjusting the degree of fatty acids (FAs) unsaturation. The ability to modify the type and quantity of cellular lipids allows cyanobacteria to avoid damage and be protected against the effects of extreme conditions. The combined effects of increased temperature and solar UVR on Microcystis aeruginosa cultures were analyzed in terms of FA content and lipid damage. The M. aeruginosa culture was incubated to natural sunlight in two outdoor water baths at 26 and 29°C during 4 days. Cells were exposed to both temperatures and three radiation treatments: full radiation (UVBR + UVAR + Photosynthetic Available Radiation, PAR), UVAR+PAR and only PAR (control). During the first two exposure days, UVAR modulates lipid damage as a function of temperature in consequence of an increase in reactive species and the FAs composition. After four exposure days the cells were adapted to both increased temperature and UVR. Thus, increased temperature and UVR changes could impact the ω6/ω3 PUFAs balance of cyanobacteria. This response can further be transferred from cyanobacteria to higher trophic levels and can influence the overall functioning of freshwater bodies.